#17367: Classes of combinatorial structures
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Reporter: elixyre | Owner:
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-6.9
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jean-Baptiste | Reviewers:
Priez | Work issues:
Report Upstream: N/A | Commit:
Branch: | c13301a1fe97f639089a691bd0f75d78cc8aa6a0
u/elixyre/class_of_combinatorial_structures| Stopgaps:
Dependencies: |
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Changes (by vdelecroix):
* status: needs_review => needs_info
* milestone: sage-6.5 => sage-6.9
Comment:
Hello,
I strongly think that creating this category is useless '''and''' I
certainly understand that it is needed. What I propose is to not create a
new category but make this featured sets with NN grading and finite slices
available. What I would rather implement is:
- making the grading set a parameter of the category `SetsWithGrading`
(in your case it would be `NN`)
- adding an axiom `FiniteSlice` to `SetsWithGrading`
That way, what you are trying to define would simply be
{{{
sage: SetsWithGrading(NN).FiniteSlices() & EnumeratedSets()
Join of Category of sets with grading Non negative integer semiring with
finite slices
and Category of enumerated sets
}}}
(.. the names are awful, but I hope that the plan is clear ...).
Related to my previous remark, you add plenty of stuff that should be
discussed at the level of `SetsWithGrading`. For example the presence of a
`.grade()` method. And that was actually already discussed while working
on #10193 (but sadly not written explicitely in the ticket): we want Sage
to support structure of objects that do not care such much about their
environment (i.e. facade sets). A good example is
{{{
sage: F = FiniteEnumeratedSet([1,2,3])
sage: F.an_element().parent()
Integer Ring
}}}
Some terminology and english weirdnesses:
- What is `denumerable`?
- Where did you found your definition of `structure`? `combinatorial
structure` would make more sense. I do not understand [comment:13
comment:13]. If you talk about structure to a random mathematician, it
will rarely end up with some combinatorics in mind.
Vincent
--
Ticket URL: <http://trac.sagemath.org/ticket/17367#comment:17>
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